* test(qa): canonicalize channel routing scenarios
* test(qa): enforce Crabline actor allowlists
* test(qa): preserve canonical flow integration
* test(matrix): use retained topology fixture id
* test(qa): preserve WhatsApp live defaults
* QA: declare channel transport policy in scenarios
* refactor(qa): keep transport policy type local
* refactor(qa): keep transport policy on leaf contract
* test(matrix): use retained routing fixture